Along an assembly line, various types of articles, such as for example, diapers and other absorbent articles, may be assembled by adding components to and otherwise modifying an advancing, continuous web of material. For example, in some processes, advancing webs of material are combined with other advancing webs of material. In other examples, individual components created from advancing webs of material are combined with advancing webs of material, which in turn, are then combined with other advancing webs of material. Webs of material and component parts used to manufacture diapers may include: backsheets, topsheet, absorbent cores, front and/or back ears, fastener components, and various types of elastic webs and components such as leg elastics, barrier leg cuff elastics, and waist elastics. Once the desired component parts are assembled, the advancing web(s) and component parts are subjected to a final knife cut to separate the web(s) into discrete diapers or other absorbent articles. The discrete diapers or absorbent articles may also then be folded and packaged.
Various methods and apparatuses may be used for attaching different components to the advancing web and/or otherwise modify the advancing web. For example, some production operations are configured to apply relatively high viscosity fluids, such as hot melt adhesives, to an advancing web. In some instances, the production operations are configured to apply hot melt adhesives to an advancing web in pre-determined patterns. These operations may include the use of systems and methods such as slot die coating, direct gravure, offset gravure and reverse gravure roll coating processes that are extensively described in the art. However, current systems and methods for applying patterned adhesives to an advancing substrate may have certain limitations.
For example, in the manufacture of absorbent articles such as famine hygiene pads, baby diapers, and adult incontinence pads, the use of gravure coating processes may be confounded by contamination of the impression cylinders by fibers separated from the substrates to be coated. Some problems associated with gravure cavities and incomplete fluid transfer are described, for example, in U.S. Pat. Nos. 7,611,582 and 6,003,513. In some instances, slot die coating may be used for patterned coating of webs in the manufacture of absorbent products. The use of combed shims in slot die transfer processes can provide fine resolution and precise transfer of fluid to the receiving substrate in the axis transverse to the direction of web travel.
U.S. Pat. No. 8,186,296 describes an apparatus for applying adhesive in a pattern to an advancing substrate, the apparatus comprising:
a slot die applicator including a slot opening defined by a first lip and a second lip;
a substrate carrier adapted to advance the substrate past the slot die applicator, wherein when a first surface of the substrate is disposed on the substrate carrier, the substrate carrier is adapted to advance a second, opposing, surface of the substrate past the slot opening of the slot applicator, the substrate carrier comprising:                a base surface; and        a pattern element, wherein the pattern element includes a pattern surface, and        wherein the pattern element protrudes outward from the base surface to define a distance, Hp, between the pattern surface and the base surface;        
wherein as the substrate carrier advances the second surface of the substrate past the slot opening, the pattern element is advanced such that the pattern surface repeatedly advances past the first lip, the slot opening, and the second lip of the slot die applicator.